Byron, in my neck of the woods in southeast Idaho the PMD spinners are two colors and usually a size apart. My understanding is that the females are usually olive while the males are rusty and a size smaller than the females. Most spinner falls I have experienced here have been a size 16 olive spinner and a size 18 rusty spinner.
Tight Lines,
Kelly.
"There will be days when the fishing is better than one's most optimistic forecast, others when it is far worse. Either is a gain over just staying home."
Roderick Haig-Brown, "Fisherman's Spring"